-> If I don't need to put mail.domain.tld for all domain i will setup a mail service, why I need to add mail.live-pics.net ?

-> oups, as I said in my first post, I didn't understand configuration of /etc/aliases file. [email protected] is neither a local account nor remote mail server. ks358431.kimsufi.com is name of my server. Do I must replace postmaster by root or user postfix?